1. Field of the Invention
The present invention is directed to toilet flushing. It finds particular application in tank-type flushers.
2. Background Information
The art of toilet flushers is an old and mature one. (We use the term toilet here in its broad sense, encompassing what are variously referred to as toilets, water closets, urinals, etc.) While many innovations and refinements in this art have resulted in a broad range of approaches, flush systems can still be divided into two general types. The first is the gravity type, which is used in most American domestic applications. The gravity type uses the pressure resulting from water stored in a tank to flush the bowl and provide the siphoning action by which the bowl""s contents are drawn from it. The second type is the pressurized flusher, which uses line pressure more or less directly to perform flushing.
Some pressure-type flushers are of the tank type. Such flushers employ pressure tanks to which the main water-inlet conduit communicates. Water from the main inlet conduit fills the pressure tank to the point at which air in the tank reaches the main-conduit static pressure. When the system flushes, the water is driven from the tank at a pressure that is initially equal to that static pressure, without reduction by the main conduit""s flow resistance. Other pressure-type flushers use no pressure tank, and the main conduit""s flow resistance therefore reduces the initial flush pressure.
While flush-mechanism triggering has historically been performed manually, there is also a long history of interest in automatic operation. Particularly in the last couple of decades, moreover, this interest has resulted in many practical installations that have obtained the cleanliness and other benefits that automatic operation affords. As a consequence, a considerable effort has been expended in providing flush mechanisms that are well adapted to automatic operation. Automatic operation is well known in pressure-type flushers of the non-tank variety, but gravity-type flushers and pressurized flushers of the tank- variety have also been adapted to automatic operation.
European patent publication EPO 0 828 103 A1 illustrates a typical gravity arrangement. The flush-valve member is biased to a closed position, in which it prevents water in the tank from flowing to the bowl. A piston in the valve member""s shaft is disposed in a cylinder. A pilot valve controls communication between the main (pressurized) water source and the cylinder. When the toilet is to be flushed, only the small amount of energy required for pilot-valve operation is expended. The resultant opening of the pilot valve admits line pressure into the cylinder. That pressure exerts a relatively large force against the piston and thereby opens the valve against bias-spring force. Pilot valves have similarly been employed to adapt pressure-type flushers to automatic operation.
Commonly assigned copending U.S. application Ser. No. 09/544,800, which was filed on Apr. 7, 2000, by Parsons et al. for an Automatic Tank-Type Flusher and is hereby incorporated by reference, describes an arrangement in which the flush valve is biased to its unseated state, in which it permits flow from the tank to the bowl, and it uses line pressure to hold the flush valve shut rather than to open it. That approach tends to make it relatively simple to have a repeatable valve-opening profile. Also, high line pressure actually aids in preventing leakage through the flush valve; unlike some other arrangements, such pressure does not tend to reduce the flush-valve seal""s effectiveness. Since the toilet""s suction generation is principally dependent on the valve-opening profile, and since this approach makes the bias mechanism essentially the sole determinant of that profile, that approach makes the valve-opening aspect of flush operation largely independent of line pressure.
As is indicated in commonly assigned U.S. patent application Ser. No. 09/716,870, filed on Nov. 20, 2000, by Parsons et al. for a Timed Fluid-Linked Flush Control and hereby incorporated by reference, moreover, that approach has applicability not only to automatic flushers but also to flushers that are manually operated.
We have recognized that this approach to flush control can be further improved so that this approach results not only in more-effective valve opening but also in more-effective valve closing. According to one aspect of the invention, a flow diverter operated by the flush valve impedes or prevents tank filling while the flush valve is in its open state. This limits line-pressure reduction that the filling operation might otherwise cause, so the line pressure available to close the flush valve tends to be better preserved.
In accordance with another aspect of the invention, a flow controller is interposed in the path by which the line pressure is applied to the flush valve to close it. The flow controller can be of any of the many types that tend to reduce pressure variation. By so including such a flow controller in that pressurizing path, a system employing that feature exhibits relatively consistent flush-valve-closing performance despite variations in line pressure.
In accordance with yet another aspect of the invention, a check valve is included in the path by which fluid to apply closing pressure to the flush valve is delivered to it. By employing this feature, the flush system can maintain flush-valve-sealing pressure despite a temporary loss in line pressure.